Rocket motor ignition is normally controlled by utilizing an igniter which gives a controlled rate of heat release which simultaneously pressurizes the motor. Nozzle closures are used to aid ignition by retaining the igniter action until proper motor pressure is obtained. The nozzle closures normally used are metal or plastic and are retained in the nozzle by mechanical design or adhesives. When the desired pressure is reached, the closure is ruptured, sheared, extruded or overcomes the bond strength if adhesive is used. Such method of motor opening can generate an unacceptable noise level.
The present invention relates to nozzle closures which reduce and control the noise level generated by rocket motors during ignition by incrementally or continuously opening the motor.
Such closures are used to reduce the shock wave effect produced internally and externally to the motor. This is particularly advantageous for motors which operate near personnel.